Concrete mixing plant



March 9, 194s.v ehMAxoNJgl; 2,437302- I CONCRETE MIXING PLANT Filed Jan. 19., 1942- 5 Sheets-Shae; l

March 9', 1948. G, MAXQN, J 2,437,302

CONCRETE MIXING PLANT Filed Jan. 19, 1942 5 sheets-s eet 2 v m 3 0 O 0 fiZmwavMaxarz J1? 1 March 9, G MAXQNI JR CONCRETE MIXING-PLANT .5 Sheets-Sheed s Filed Jan. 19,1942

mm hm hm mm wm mm :Mum EZEHWEY MiXmu I'? March 9, 1948.

G. MAXON, JR 2 I CONCRETE MIXING PLANT Filed Jan. 19, 1942 5 Sheets-Sheet 5 Patented Mar. 9, 1948 UNITED STATES PATENT OFFICE CONCRETE MIXING PLANT Glenway Maxon, Jr., Milwaukee, Wis., assignor to The T. L. Smith Company, Milwaukee, Wis., a corporation of Wisconsin Application January 19, 1942, Serial No. 427,298

' batching mechanism whichin turn receives the aggregates from elevated supply bins.

In the operation of the plant the battery of mixers is fed successively, the entire contents of the aggregate supply hopper being emptied first into one and then the next mixer.

Heretofore this sucecssive discharge of the hopper contents into the several mixers was effected by means of a rotatable chute structure at the bottom of the supply hopper and swinging chutes under the hopper, one connected with each mixer. By rotating the turnhead as this rotat- 4 Claims. (Cl. 259152 able chute structure was called, the hopper contents could be discharged first into one and then another mixer.

However, this manner of distributing the feed to the mixers was objectionable. Proper alignment between the various parts was difi'icult to establish and maintain inasmuch as the swinging chutes were interlinked with the tilting mixers and the hopper was connected to the batching mechanism.

Another objection to this past construction resides in the necessity for revolving the turnhead chute, and in the fact that the swinging chutes and the manner in which they are mounted limited the extent to which the mixers could be brought together.

With these and other objections to past and existing apparatus of this type in mind it is an object of the present invention to provide an improved concrete mixing plant wherein the distributing unit by which the aggregates are fed to the several mixers of the battery is entirely independent of the batching mechanism thereabove and also independent of the concrete mixers so that the problems of accurate alignment are materially simplified.

Another object of this invention resides in the provision of a distributing unit for the purpose described wherein the discharge of the supply hopper is effected "through any one of a number of fixed spouts each of which is directed toward the mouth of one of the mixers.

Another object of this invention is to provide a novel movable chute structure for bridging the gap between the end of each spout and the mouth of its associated mixer, and an improved manner of actuating the same so as to obviate mechanical connection of the chute structures with the mixers.

Another object of this invention is to provide a distributing unit of the character described which enables a closer clustering of the mixers to thus effect desirable compactness.

Still another object of this invention resides in the novel formation of the supply hopper per se with particular reference to the manner in which the valve means or trap doors, which con-.

trol communication between the hopper and the spouts, coact to form the bottom of the hopper.

With the above and other objects in View, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such ehanges in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment ofthe invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a side View of a concrete mixingplant embodying this invention; I

Figure 2 is an enlarged view of the distributing unit and showing its relationship to the concrete mixers;

Figure 3 is a top plan View with parts broken away and in section of the distributing unit;

Figure 4 is a perspective View illustrating part of the distributing unit, said view having portions thereof broken away and in section; and I Figure 5 is a perspective View also illustrating part of the distributing unit and showing particu larly the manner in which opening and closing,

of the trap doors is coordinated with the positioning or shifting of the'bridging chute structures.

Referring now particularly to the accompanying drawings in which like numerals indicate like parts, the numeral 5 designates the supporting structure for an elevated material supply bin 6 which, as is customary, is divided by partitions (not shown) into compartments all of which functioning of the scales.

Under a hole in the mixer floorisa tunnel-like concrete receiving hopper it, the outlet of which may be arranged to discharge into transit vmixers as shown in Figure l, or to any other desired receiving point.

The mixers 9 are grouped about the funnel-like hopper .lfl with their combined charging and discharging mouths .li! facing a common center. Thus each mixer .uponbe'ing tilted to its discharg ing position may empty into the hopper ill.

While the mixers shown are of the front end loading tilting type, any other suitable time of mixer maybe employed; for instance, non-tilting mixers of the type used in truck mixers wherein drum rotation 'in one direction effects .znixing, while revolution in the Opposite direction effects discharge of the .drum contents could be The important consideration. is that the mixers have combined charging and discharging mouths facing a common center.

A distributing unit, indicated generally by the numeral 12 andwith which the present invention is particularly concerned, is arranged to receive thea gregates from'the discharge it of the batching mechanism and to feed the same into the mouths of the mixers. This distributing unit is mounted-n a supporting structure including 'four legs 14 resting on the mixer floor '8 and "isho-used within a box-like structure .15.

This box-like structure i is made of she t steel or the like and has vertical walls it and a bottom 11. Inasmuch as thepresent adaptation of the invention embodies a battery of four mixers, this "box-like structure is square. If three mixers constituted the battery, the box-like structure would be triangular, or it might "be circular, if desired. 7

In any event, fixed spouts l3 extend-downwardly and outwardly from holes 19 in the bottom -.wall l1. One such spout is provided for each-mixer and each spout is directed toward the mouth of its associated mixer but is spaced far enough therefrom to allow the mixer to tilt between mixing-and discharging positions.

Supported in the top of the box-like structure is an aggregate supply hopper -25. Inasmuch .as the box structureinthis case-is square, the supp y hopper hasan invertedpyramida'l shapeand consists of four downwardly sloping flat walls 21! the upper edges of which are joined to the vertical side walls it of thebox-like structure.

The lower edges of these sloping walls'2'l terminate a substantial distance above the bottom if! of the box-like structure thus leaving the bottom of the hopper open to be closed by four trap doors or gates 22 which 'conjointly form the bottom of the hopper. These trap doors or gates constitute valve means to disconnect the interior of the hopper from the spouts as each trap door is located above one of the spouts.

Each trap door is hinged as at '23 to the lower 4 edge of its respective hopper wall 2| to swing to and from its closed position. Attention is directed to the specific shape and formation of the trap doors. It will be seen that the upper section 24 of each trap door has a trapezoidal shape and that its lower portion 25 is triangular. The upper trapezoidal portions, when the trap doors:are-;closed, form substantially continuations of the sloping walls 2|, but the triangular lower portions 25 are at a substantially lesser slope and serve as the extreme bottom of the hopper. Consequently, in the event a large piece of aggregate should remain lodged on the lower portions of the closed trap doors while one trap door is open, such piece of aggregate will be :more ant to :be supported in a manner allowing free closure of the open trap door; or in other words, the lesser slope of the lower triangular portions of the trap doors precludes the possibility of aggregates being wedged between the edges .or the doors during closure.

While it is .preferableto have the trap doors con'jointly form the entire bottom portion of the hopper, part of the bottom might be formed by stationary wall sections without seriousefiect, provided the doors are of sufficient size to insure unrestricted discharge of the hopper contents upon the opening of anyone door.

The space within the. square box-like structure under the hopper .is divided into four .compartments by diagonal partitions 2B. The lower edges of these partitions extend below the bottom ll of the box-like structure .to ,merge with the adjacent walls of the spouts.

The outer corners of the .tour compartments or spaces formed in .the box-like structure by these diagonal partitions are covered by sloping conical walls 27 which extend up from the edges of the holes T9. The spaces or compartments into which the box-like structure .is divided by the diagonal partitions thus roughly serve as funnels for the spouts 18 to direct the aggregates down into the spouts.

As noted herein'before, the lower ends of the spouts are spacedfrom themouths of the .mixers to allow the mixers to tilt. It is thus necessary to provide some means .for bridging the gap between the ends of the spouts and .the .mouths of the mixers. This is accomplishedin the present instance by movable .chute sections or structures 23 arranged to swing from retracted positions embracing the spouts, to extended bridging Dositions leading into the mouths of the mixers.

Each chute structure is pi-votall-y supported :as at 2% on a shaft .30 which in turn is supported in bearings .31 fixed to upright channel members 32 welded or otherwise secured to the vertical side walls Iii of the box structure.

As best shown in Figure 5, the actual support for the bridging-chute structures consists :of arms 33 welded or otherwise fixed to the sides of the chute structures and constituting Part of bell cranks mounted .on the ends of the shaft or rod 351. The other arms 34 of these bell cranks are connected by links 35 with eccentrics 36.

The eccentrics 36 are fixed on the outer ends of a rockshaft .31 journalled in suitable bearings 33 also secured to the channel members 32. The rockshaft 3'! has a lever 39 fixed thereto. the end of which is connected by :a link 40 with the trap door as at 4|.

Thus, by oscillating the rock-shaft 37 it is possible to actuate both the trap "door and its bridging chute structure.

The linkage above described for efiectlngthis result is so proportioned and arranged that during opening of a trap door its chute structure is swung out to bridging position extending its outer end into the mouth of the mixer and during closure of the trap door the chute structure is retracted clear of the mixer mouth.

As will be readily apparent, each trap door and its associated movable bridging structure has its own actuating mechanism.

The operation of the actuating mechanisms may be eifected in any desired manner, as by means of air cylinders .42. Each cylinder is anchored to a cross-shaft 43 and has its ram 44 connected to the outer end of a lever 45 fixed to the rockshaft 31.

In practice, the cylinders'are interconnected so as to preclude simultaneous operation of two or more actuating mechanisms.

In the operation of the plant, the aggregate supply hopper is charged with the premeasured or batched aggregates, during which time all of the trap doors except one must be closed. If all of the traps doors are closed then one of the trap doors is opened whereupon the contents of the hopper discharges into one of the mixers, opening of the trap door having been accompanied by swinging of the associated movable chute structure into its extended position bridging the gap between the fixed spout and the mouth of the mixer.

It is preferable to coordinate the controls of the batching mechanism release with the controls for the trap doors so that one trap door is opened concomitantly with release of the batches. In this way the charging cycle is shortened without objection for it is sufiicient if the supply hopper serves merely as a passageway to direct the aggregates to the mixer being charged, the closed trap doors guiding the aggregates toward the discharge opening provided by the open trap door. It is thus apparent that the hopper serves as a charging device .or charging hopper common to all of the mixers.

Simultaneously with the charging of the dry aggregates in the manner described, water is injected into the mixer in any suitable manner as by means of a supply pipe 46 extending down alongside the side wall IS with its discharge end positioned to direct the water into the mixing drum.

Directly after the first mixer is charged in the manner described the open trap door is closed and the supply hopper again loaded. Then while the first mixer is in operation, the next mixer is charged and the procedure repeated sequentially, as will be readily apparent.

It will also be apparent to those skilled in the art that inasmuch as this invention does not employ a turnhead chute which had to be controlled and operated from the batching floor above, the entire distributing unit may be built and assembled by the manufacturer of the mixers, and that inasmuch as the distributing unit is entirely independent of the batching floor the establishment and maintenance of the required alignment between the mixers and the distributing unit is a simple matter.

What I claim as my invention is:

1. An aggregate supply hopper having a wall sloping downward toward the center: a plurality of trap doors each forming part of the bottom of the hopper and each of suiiicient size to enable discharge of the hopper contents upon opening thereof, said trap doors having upper and lower portions at different degrees of slope with the lower portions thereof having the lesser slope so that a large piece of aggregate resting on the bottom portions of the closed trap doors does not prevent closure of an opened trap door.

2. A hopper for handling aggregates of various sizes comprising: an upper portion having fixed walls sloping downwardly toward the center; and a plurality of trap doors each forming part of the bottom of the hopper and each large enough to allow the contents of the hopper to discharge upon opening thereof, each of said trap doors having an upper portion forming substantially a continuation of the fixed hopper wall thereabove and a lower portion sloping at a lesser angle than said upper portion, said lower portions of the trap doors oonjointly forming the extreme bottom of the hopper.

3. A distributing unit for feeding aggregates to a battery of concrete mixers comprising: a supporting structure; a box mounted on said sup porting structure; a hopper mounted in the upper portion of the box; a pluralityof trap doors each constituting part of the bottom of the hopper and each arranged to swing inside said box to and from a closed position forming part of the bottom of the hopper, each of said trap doors being of sufiicient size to allow the contents of the hopper to pass therethrough; and spouts fixed to the bottom of the box for directing the aggregates toward the mixers, one of said spouts being under each trap door.

4. A distributing unit for feeding aggregates to a battery of concrete mixers comprising: a supporting structure; a box mounted on said supporting structure; a hopper mounted in the upper portion of the box; a plurality of trap doors each constituting part of the bottom of the hopper and each arranged to swing inside said box to and from a closed position forming part of the bottom of the hopper, each of said trap doors being of sufiicient size to allow the contents of the hopper to pass therethrough; spouts fixed to the bottom of the box for directing the aggregates toward the mixers, one of said spouts being under each trap door; and means within the box and under the hopper for guiding materials into the spouts so that said spouts have substantially a funnel-like formation.

' GLENWAY MAXON, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

